1. The Field of the Invention
The present invention relates to the field of sensors and sensing systems. More particularly, embodiments of the invention relate to systems and methods for powering and communicating with sensors including remote sensors.
2. The Relevant Technology
In general, a sensor is a device that generates an output based on some type of input. Sensors have been developed that can respond to a wide range of inputs including, by way of example, nuclear, electromagnetic, chemical, biological, thermal, and mechanical inputs. The ability to respond to many different types of input has made sensors an important aspect of technology. As a result, sensors are increasingly used in a wide range of activities that include, for example, medicinal purposes, environmental purposes, commercial endeavors, industrial activities and biological functions.
In each of these types of activities, there is a growing dependence on the ability to collect, monitor, and analyze data. Sensors help in this endeavor by facilitating and improving the process of collecting and analyzing the data. Sensors improve the ability to collect and analyze data for several reasons. For instance, sensors are usually able to detect a situation more rapidly than a person can detect the same situation. Sensors can also detect subtle changes as well as detect minute quantities that a person cannot discern. In addition, sensors can be deployed in locations and situations where it is often impractical to deploy people.
The data collected by sensors can be used in various ways. Sensor data can be collected over time to monitor trends or to measure changes over time. For example, traffic patterns are collected with sensors over time before implementing a form of traffic control. Collecting the traffic data over time enables a traffic control system to be more efficient. Sensors can also collect data that can be analyzed and used to make quick decisions. For example, automobiles have multiple sensors that collect information that is used to determine when an air bag should be deployed. Clearly, the air bag should not be deployed unnecessarily but only when an accident occurs. As a result, the data collected by the multiple sensors is analyzed collectively to distinguish, for instance, between a true accident and when someone is simply leaning forward.
While sensors can have a beneficial impact on the ability to collect, monitor, and analyze data, there are some limitations that have not been overcome. Some of these limitations relate, for example, to a sensor's power source and to the sensor's communication abilities. Power and communications are problems because the output of many sensors is often electrical in nature and the ability of a sensor to transmit or receive data is often dependent on the power supply. In some instances, power is achieved usig a photodiode that is separated into various segments. These segments usually connected serially so that the voltages add together. One drawback to this approach is that an optical beam is needed to generate current in the photodiodes. If the optical beam is not properly aligned, a loss of electrical power occurs. In other words, the segment that is aligned the worst limits the overall power. The generated current is limited by the element that is poorly aligned.
In spite of the difficulty of powering sensors and communicating with sensors, an electrical output is often desirable because electrical signals can be easily received and processed by computers. In other words, sensors with an electrical output can more easily communicate its data to a computer for analysis. This assumes, however, that the sensor has sufficient power available to communicate its data. For example, in the case of sensors used to control the deployment of an air bag, power and communication are not limiting issues because the car itself provides a power supply that easily meets the power requirements of the sensors over time. At the same time, the power supply of the car enables the sensors to communicate collected data at any time.
In contrast, there are many sensors that have a limited power supply, such as a battery, and therefore have a limited life. A battery enables a sensor to operate for several years as long as the sensor only collects data intermittently and for short periods of time in order to preserve the power of the battery. In these cases, battery power is often conserved by having the sensor “sleep” when not collecting data. A microcontroller, for example, may only need microamps of current during short periods of time. As a result, the battery and therefore the sensor can have a relatively long life.
Unfortunately, battery life drains much more quickly if the sensor is required to transmit the collected data using the battery. In this case, milliamps of current may be required to transmit/receive data instead of the microamps required to operate a microcontroller. Because the transmission and reception of data drains a battery rather quickly, a burden is created in maintaining the effectiveness of the sensor. In other words, the sensor must be physically retrieved in order to extract the collected data. Someone is also needed to change the battery. There is therefore a need for systems and methods that can overcome the effects of a limited power supply in sensors.